The present invention relates to the field of hydraulics. In particular, the present invention relates to a feeder for a camshaft adjuster, the use of a flow resistance element in a feeder for a camshaft adjuster, a camshaft adjustment device with a feeder for a camshaft adjuster, and a flow resistance element.
Camshafts with their cams are used in an internal combustion engine for the purpose of opening gas-exchange valves against the force of valve springs, wherein these gas-exchange valves are designed for pushing out the combusted gases and drawing in fresh gases separately. Rigid control times for the valves always represent a compromise in design with respect to the achievable maximum force or torque and its position in the usable rotational speed band, as well as the achievable output at nominal rotational speed.
Therefore, rotating camshafts have been developed, which can change the control times for the valves through rotation of the camshaft depending on the engine rotational speed. Such a hydraulically operated device for variable adjustment of the control times of an internal combustion engine, a so-called camshaft adjuster, is known, for example, from EP 0 806 550 or DE 196 23 818.
During the operation of the internal combustion engine, alternating moments act on the camshaft, which appear, for example, through friction forces in the contact of the cams with the closing valves. These alternating moments are generated through the rolling of the cams on the cam followers, for example, compensation elements, for compensating the valve lash. The pressure spikes generated by the alternating moments are described, for example, in EP 0 590 696.
The pressure spikes are generated in the pressure chambers of the camshaft adjuster and can lead to the undesired result that the actual chamber to be pressurized is partially evacuated for the period of the pressure spike. The adjustment speed, with which a camshaft can be adjusted to an advanced or retarded position, decreases and the phase alignment is negatively affected. In addition, the pressure spikes are also transmitted to other pressure consumers that could therefore become damaged.
It is known to integrate non-return valves in the external pressure circuit or in the external pressure line of the camshaft adjuster. Examples here can be taken from EP 0 590 696, EP 1 291 563, or EP 1 284 340.
A central valve that is integrated in the screw for the camshaft attachment is known, for example, from DE 199 44 535 C1.